Wire grinding machine



March 18, 1969 A. CONTI 3,432,971

WIRE GRINDING MACHINE Filed June 29, 1966 Sheet of :5

Lehm

@M /MAL /L March 18, 1969 A. CONTI 3,432,97

WIRE GRINDING MACHINE Filed June 29, 196e sheet 2 of s March 18, 1969 A CONTl WIRE GRINDING MACHINE Sheet Filed June 29, 1966 United States Patent O 15,222/ 65 U.S. Cl. 51-80 11 `Claims Int. Cl. B24b 7/02, 9/00 ABSTRACT F THE DISCLOSURE A metal wire grinding machine in which a drum is driven in rotation about its axis and supports on one side of a radial wall therein, a pair of grinding wheels arranged symmetrically and adjustably, with respect to the axis of rotation of the drum, and on the opposite side of the wall a driving means for rotating the wheels about their respective axes which are offset from the axis of rotation of the drum. The wheels are Supported in heads which in turn are supported in the drum and resiliently urged against the lwall therein, said heads containing a transmission for the drive between the wheels and the drive means therefor.

This invention relates to a machine for grinding metal wires and the like.

It is known that in modern industry the use of hotrolled wire rods of special or alloyed Steels is ever increasing for the production of tools and of rollers and balls for roller-bearings and ball-bearings, respectively.

It is also known to those skilled in the art that hotrolled wire rod exhibits superficial defects with inclusions of oxidized layers at variable depths, decarburized spots and the like. The use of modern high-speed rolling machines has further contributed to impairing the supercial condition of the wire rod thus giving ris'e to superficial ridges and creases which, though of restricted depths, are still very objectionable to the utilizing of the wire rod.

There are industries which utilize the Wire rod and which necessitate, to the end of a subsequent processing of the metal wire, an absolutely pure rod devoid of any superficial defects and having a suiciently smooth surface within the requested tolerances.

In order that these requirements may be fulfilled, two different modes are currently employed. For example, in one the wire rod is cold-drawn but, inasmuch as it is not possible to do away in this manner with all the defects aforementioned, the industries which utilize the drawn wire are compelled to use a wire having a diameter greater than that which would be theoretically required, that is, they are required to resort to an increase of the machining allowance so as to remove all the supercial defects by a subsequent machining. To this end, it is necessary to cut the continuous-length wire rod or wire into bars of a limited length which are ground on the so-called centerless machines; these have the great drawback that they are not enabled to operate on a whole wire coil with continuity. The machines which utilize the ground wire thus cannot work automatically or continuously because 3,432,971 Patented Mar. 18, 1969 they cannot be fed with a ground wire having a considerable length and forwarded continuously.

A novel machine has been recently adopted in which the continuous wire is caused to pass into a drum which rotates about its own axis and the latter coincides with the axis of the wire, special steel tools being provided within the drum for removing from the wire rod surface a thin superficial layer: this operative step, however, is such as to produce a noticeable waste of wire material since the tip of thel tool must always work below the superficial oxidized or decarburized layer of the wire, said layer being very hard and, furthermore, this step cannot be regarded as anything more than a roughing operation which does not provide a smooth surfaced wire within the required tolerance limits.

An object of the present invention is therefore to provide a machine capable of operating on the common hot-rolled wire rod of alloyed or special steel, to produce a wire exempt from any superficial defect, exhibiting a smooth surface and within very close tolerances relative to the diameter of the obtained Wire.

Another object is to provide a machine capable of being continuously fed by a coil of wire rod or continuous wire and capable of producing ground wire continuously and in infinite lengths.

A further object is to provide a machine capable of machining wires having different diameters, made of steels of different qualities.

Still another object is to provide a machine for grinding a wire by removing a minimum amount of wire from the surface of the Wire being machined.

The foregoing and other objects are achieved with a wire grinder which comprises a bedplate, a drum mounted on said bedplate and rotatably about its own axis, members for guiding a metal wire coaxially with said drum, two grinding wheels arranged symmetrically with respect to the drum axis and borne by carriers mounted thereon, moving means for rotating said drum about its own axis, means for rotating said grinding wheels about their respective axes, and driving means for driving the metal wire along the axis of said drum.

The structural features of said machine and the advantages stemming from its use will become fully apparent from a consideration of the ensuing disclosure which describes, by way of example only and without any limitation, an embodiment of said machine, reference being had to the accompanying drawing, wherein:

FIGURES 1 and 2 are radial cross-sectional views of the machine with its rotatable drum somewhat angularly shifted in one figure with respect to the other one,

FIGURES 3 and 4 are two diagrammatical axial sections of the machine, which also show the drum somewhat angularly displaced in one figure with respect to the other figure.

As can be seen in the drawings, the machine comprises a bedplate 20 which, through bearings diagrammatically designated by the numerals 22, 23, 24 and 25 (see particularly FIG. 4) carries in a freely rotatable way a hollow shaft 11. At the free end of the shaft 11, on the right side as viewed in FIGS. 3 and 4, is overhangingly affixed a drum 10 coaxial with said shaft 11. At the opposite end of the shaft 11 (on the left as viewed on FIGS. 3 and 4) is mounted, freely rotatable on bearings 29, a

portion 27 of an electromagnetic clutch 16, the other portion of which, indicated by the reference numeral 28, is rigidly aflixed to the shaft 11. On the portion 27 of the electromagnetic clutch is affixed a Worm gear 15 having helical teeth, meshing with a worm 26 driven in rotation by a motor (not shown in the drawings to simplify the same). When the electromagnetic clutch is deenergized, the portion 27 thereof rotates idly on the bearings 29 and thus on the shaft 11. When, conversely, the clutch is energized and coupled, the rotary motion of the worm 26 is transferred from the portion 27 to the portion 28 of the electromagnetic clutch 16 thus driving in rotation the shaft 11 and therewith the drum 10: the use of the electromagnetic clutch also permits to obtaining a gradual drive in rotation of the drum 10.

The drum 10 comprises a radial wall having two holes with circular housings 39 (FIG. 3) diametrically opposite to one another: in each of said holes is threaded and housed a cylindrical shank 33 of a grinding-wheelcarrying head 1 which, as viewed from the side, has the shape of a large Z as can be seen in FIG. 3. One of said grinding-wheel-carrying heads will be described in greater detail hereinafter. At its end remote from shank 33, the grinding-wheel-carrying head supports, by balland roller-bearings, a grinding wheel carrier chuck 4 which, through a flanged hub, carries a grinding wheel 2: the grinding-wheel-carrying chuck is iixedly held by a screwthreaded sleeve 34 screwed onto the wheel-carrying head. The wheel-carrying head 1 comprises a plurality of housings in which are housed (FIG. 3) rods 48 having an enlarged head 51 at one end: between said head 51 and the body of the wheel-carrying head 1, a spring 50 is interposed, which is in the compressed condition. The end of each rod 48, remote from head 51, protrudes out of the body of the wheel-carrying head 1, and is screwthreaded and inserted into an elongated perforation 49 formed in the radial wall adjacent housing 39. A nut 52, screwed onto the screw-threaded end of the rod 48 acts in such a way that the spring 50 urges the wheel-carrying head against the radial wall of the drum thus impeding, by friction, free movement of the cylindrical portion 33 and thus of the wheel-carrying head 1 itself in housing 39. On the shaft of the wheel-carrying chuck 4 is keyed a gear 4S (FIG. 3) which engages another gear 44 keyed, in turn, on an idle arbor 46 borne in the wheel-carrying head 1 and on which are also keyed two gears 42 and 43. On a splined arbor 40, also supported by the wheel-carrying head 1, is mounted a pair of gears and 41 which lcannot rotate with respect to the arbor 40 but can be axially shifted thereon. Said operation can be effected when the machine is at standstill by removing, from the wheel-carrying head, a front lid, then causing the wheel 5 to mesh with the gear 42, or, alternatively, the gear 41 with the gear 43, by fixing the gears on the arbor 40 in the desired position and then replacing the front lid on the wheel-carrying head. In consideration of the fact that the arbor 40 is the driver shaft which transfers the rotational drive to the wheel 2,- as will be explained hereinafter, it can be appreciated that the assemblage of gears described above is such as to constitute a speed-change gear with two speeds, shown in its neutral condition in FIG. 3 and capable of transquitting to the wheel 2 a rotary drive at two different speeds, from a constant r.p.m. of the arbor 40.

The arbor 40 is driven by an electric motor 3 via a clutch 47, said motor 3 being secured to a ilange 36 which is aiiixed to a radial wall 37 of the drum 10. The two electric motors 3 which actuate the two grinding wheels 2, receive their feeding current from a. set of collector rings 17 which are rigidly borne by the drum by a set of supporting brackets 53. The motors are connected by cables to the collector rings 17 on which brushes, (not shown in the drawing), are allowed to slide and carry to said rings the feeding current.

The wheels 2 are partially enclosed and protected,

each by an apron 35 afiixed to the attendant wheel-carrier head and having the shape which can be seen in FIGS. 1 and 3.

To the cylindrical portion 33 of each wheel-carrying head 1 is affixed, by bolts, an end of a lever 6 (FIGS. 2 and 3), which, at its other end, has a longitudinally extending spline (FIG. 2) in which is housed freely slidable and rotatable a pivot rigid with a nut 7 having a cylindrical screw-threaded hole in which a screw-threaded arbor 8. borne by the drum 10, is inserted (FIGS. 2 and 4), to whose outermost end closest the drum 10, is rigidly attached a hand-wheel 9 having a pointer (not shown in the drawings) which, in cooperation with a graduated scale solid with the drum 10 permits reading the angular position of the screw-threaded arbor 8. By manipulating the hand-wheel 9 (when the machine is stationary), a sliding movement of the nut 7 along the screw-threaded arbor 8 is obtained, thus giving rise to a rotation of the lever 6 and consequently also of the wheel-carrying head 1 about the axis of the cylindrical portion 33, against the friction existing between the contacting surfaces of the wheel-carrying head 1 and the radial wall of the drum 10 wherein the housing 39 have been formed. The rotation of the two wheel-carrying heads causes an approaching or retracting movement of the two grinding wheels 2, one with respect to the other, the rotation taking place in such a way that the plane passing through the axes of the two wheels 2 is caused to pass, irrespective of the angular positions of the wheel-carrying heads, through the same ideal line which coincides with the axis of the metal wire 21 which will be discussed hereinafter (FIGS. l and 2).

To the same radial wall of the drum 10 through which the housings 39 are formed, are affixed, in a position diametrically opposite one another, two brackets 12 each supporting a blade 13 extending towards the axis of rotation of the drum and lying in the common plane of tangency of the two grinding wheels (FIGS. 1 and 4). As can be seen particularly in FIG. 1, the confronting ends of the two blades 13 are spaced from one another by a distance equal to the diameter of the wire 21 to be ground, so that the wire cannot undergo any transversal movements inasmuch as the confronting ends of the blades 13 and the confronting sur-faces of the grinding wheels 2 prevent this movement. As can be readily appreciated, the blades 13 are contained in a plane which is substantially perpendicular to the plane -containing the axes of the grinding wheels 2. Each blade 13 is rigid (FIG. 4) with a blade-carrier which, via a screw 14, and can be radially displaced when the machine is stationary, so as to cause the free end of the blade to approach or be separated from the axis of the drum 10.

Internally and coaxially with the hollow shaft 11 is fixedly carried, with respect to the machine framing, a tubular member 30 which, at the inner end of the machine, carries members 31 capable of carrying and guiding the metal wire 21 which passes through the tubular member 30 and comes out of the machine by being displaced in the direction of the arrows F, by the action of suitable means (not shown in the drawings to simplify the showing), the wire being also carried and guided between the blades 13 and a supporting and guiding member 32 aixed to the machine bedplate at the right in FIGS. 3 and 4. Member 32 acts as a nozzle through which water is injected to cool the ground wire and dispose of the material and debris ground by the wheels 2, said material being collected at the bottom of the machine in a specially provided tub (not shown). Water is delivered to the member 32 through a conduit 61 by a conventional delivery pump.

During the operation of the machine, the metal wire 21 which is advanced in a rectilinear and continuous Way along the axis of the drum 10, is rapidly and evenly ground by the grinding wheels 2 which are endowed with a rapid rotary motion about their own axes and also with a revolution movement about the axis about the drum 10, and thus, of the wire 21. In practice, it has shown that it is possible to easily grind wires of special and alloyed steels by changing, as necessity demands, and according to the procedure outlined above, the speed of rotation of the wheels. Obviously, once a wire has been ground, if another wire having a considerably different diameter is to be ground, it is necessary to manipulate the handwheels 9 and the screws 14 so as to bring both the grinding wheels 2 and the blades 13 to a suitable mutual spacing. `It should also be noted that, with coarse grit wheels and wire 21 fed at a high speed to the machine, the hot-rolled wire rod fed into the machine undergoes an operation which could be considered a peeling and in this case the machine could be properly employed in steel mills and drawing mills.

If, on the contrary, -ine grit wheels are used and the wire rod to be ground is caused to advance at a speed lower than that of the preceding case, which can be measured experimentally, the wire is in reality ground and all the superficial defects are eliminated: under these conditions the machine finds its more appropriate application in the wire drawing mills and in industries which use ground wire, and these can have at hand a ground vwire of infinitive length, produced by a Continous process.

It is also important to note that the machine advantageously exploits what generally is considered a drawback of the materials used in machine constructions, that is the exibility of said materials. During the operation of the machine, the rotation of the drum 10 about its own axis induces a resilient bending of the grinding-wheel carrying heads 1 due to the effect of the centrifugal force which is especially due to the mass of the wheels 2. The higher the rotational speed of the drum, the greater the sag of the wheel-carrying heads and thus the greater the stroke of the wheels towards the outside with respect to the position occupied by the wheels at standstill; the position of the wheels during the operation of the machine is obviously constant if the rotational speed of the drum is constant along with the other conditions of the machine. It is apparent now that during the grinding operation of the Iwire, the grinding wheels wear out and their diameters are decreased: until such time as the decrease in diameter is confined within narrow limits of the order of hundreths or a few tenths of one millimeter, it is possible to obtain from the machine a ground wire of constant diameter without having to stop the machine and act on the handwheels 9 so as to readjust the machine. As a matter of fact, when it is noticed that the ground wire coming out of the machine increases in diameter to the tolerance limits (a consequence of the fact that the diameters of the grinding wheels have been decreased), it is suicient to decrease the speed of rotation of the drum 10v so as to diminish the sag of the wheel-carrier heads 1, whereupon a ground wire of the desired diameter is thus obtained again.

As an example of the mode of operation ofthe machine, let us assume it is desired to grind a hot-rolled wire rod, 7 mms. in diameter to obtain a wire of a diameter of 6.7 mms. With the machine at standstill, a section of previously ground wire having a diameter of 6.7 mms. is introduced between the grinding wheels 2 and the blades 13, and then, by acting on the handwheel,9 and the screws 14, the grinding wheels 2 and the blades 13 are brought into contact with the surface of said wire which is then removed from the machine. If the maximum speed of rotation of the drum during the operation of the machine is, say, 400 r.p.m., the centrifugal force will give rise, at this speed, to a sag of the wheel-carrying heads and thus will cause the wheels 2 to be pushed outwardly through a distance which has been determined by trial and error during the construction of the machine. Let us assume, for example, that at 400 r.p.m. of the drum, the wheels are thrust outward by 1 mm. each, with respect to the rest condition. Then, after having removed the section of ground wire as suggested above, the graduated handwheels 9 are manipulated so as to give rise to an approaching movement of the grinding wheels to the axis of the drum by 1 mm. The machine is now started at 400 r.p.m. and the grinding wheels are automatically shifted 6.7 mms. apart from one another. At this stage the wire rod to be ground is fed into the machine between the grinding wheels and the machining proceeds as detailed above.

I claim:

1. A metal wire grinding machine comprising a bedplate, a drum supported in said bedplate for rotation about an axis, means for driving said drum in rotation about said axis, means for guidably advancing a metal wire, to be ground, coaxially through said drum, said drum including a radial partition wall, a pair of grinding wheels, a head carrying each wheel, the heads being supported in diametrically opposed relation in said drum for rotation about respective axes which are offset from said axis of rotation of said drum, means urgng each head against said wall to resist rotation of said head relative to said drum, said heads supporting said wheels on one side of said -wall for rotation about respective axes offset from those of the heads in the drum and in symmertical disposition relative to the axis of rotation of said drum and in a common plane therewith, means for angularly adjusting the heads in said drum to vary the position of said wheels in said plane relative to the axis of said drum, and means in said drum supported onthe other side of said wall for driving said wheels in rotation about their respective axes.

2. A machine as claimed in claim 1 wherein said means for angularly adjusting the heads in said drum comprises a lever for each head, each lever having one end coupled to its associated head and an opposite end which is displacealble in said drum to produce rotation of the associated head, in opposition to the means which urges each head against the wall, and consequent displacement of the Wheel suported by said head.

3. A machine as claimed in claim 2 wherein said means for angularly adjusting the heads in said drum funther comprises for each head a rotatable threaded arbor radially disposed in said drum and a nrut threadably engaged with said arbor and secured to the associated lever at the opposite end thereof.

4. A machine as claimed in claim 1 comprising transmission nieans in said head between the wheels and the driving means therefor.

5. A machine as claimed in claim 4 wherein said driving means is a prime mover and said transmission means comprises a drive shaft in said head driven in rotation by said prime mover, each said wheel having a driven shaft and gear means coupling said drive and driven shafts for transmitting drive therebetween.

6. A machine as claimed in claim 5 wherein said gear means comprises a speed-change gear assembly for varying the drive to said wheels.

7. A machine as claimed in claim S wherein said prime mover is an electric motor, said driving means comprising colleotor rings coaxial with said drum, sliding brushes on said rings adapted for connection with an electrical cource and electrical connection means between the collector rings and said motor.

8. A machine as claimed in claim 1 wherein said means which guidably advances the metal wire comprises two blades supported from said drum in alongitudinal plane of the drum passing through the axis of rotation thereof, and means for varying the position of the blade relative to the axis of rotation of said drum.

9. A machine as claimed in claim 1 wherein said means for `driving said drum comprises a shaft coaxiallymounted Within said drum and drivingly coupled thereto, bearings in said ybedplate supporting said shaft and means yfor driving said shaft in rotation.

10. A machine as claimed in claim 9 wherein said means for driving said shaft in rotation comprises a driven Worm, 2,086,492 7/ 1937 Ekholm 51-90 a worm gear in mesh with said Worm, andi clutch means 2,383,927 8/ 1945 Carlson 51--90 X between said Wonm gear and said shaft. 2,427,283 9/ 1947 Hopkins 51-103 11. A machine as claimed in claim 1 comprising means 2,612,730 10/ 1952 Lowe 51-90 X adjacent said wheels on a side thereof opposite said Wall 2,860,456 11/1958 Bergman 51--164 for supplying a coolant, wash, liquid to said wire as it exists from said Wheels. LESTER M. SWINGLE, Primary Examiner.

References Cited D. G. KELLY, Assistant Examiner.

UNITED STATES PATENTS 10 U.s.c1.x.R.

701,290 6/ 1902 Buck 192-184 51-90, 102 721,678 3/1903 Douglas 310-92 X 

